Communication system, device and method

ABSTRACT

A communication system such as a telephone system has at least a base station and a communication device to communicate with the base station, the communication device comprises an RF power amplifier having an RF output for coupling to an antenna and an RF output power control input, a power supply having a power supply terminal, a control input and a supply output coupled to the RF output power control input for controlling an RF output power on the RF output in dependence on a signal on the control input of the power supply, a data receiver means for coupling to the antenna, the data receiver means having a data output for providing data received from the base station which represents information about said RF output power, and a table means containing a listing of possible power supply control input values related to possible RF output power values, the table means having a table selection input coupled to the data output of the data receiver means and a table output coupled to the control input of the power supply for using said RF output power related information to select that power supply control input value in the table means which corresponds to a desired RF output power value.

The present invention relates to a communication system outlined in thepreamble of claim 1.

The present invention further relates to a communication device outlinedin the preamble of claim 9, which is suitable for application in thecommunication system and to a method outlined in the preamble of claim11, and to a communication method.

Such a communication system and device are known from U.S. Pat. No.5,251,331 disclosing in particular a communication system such as acellular radio system, provided with communication devices embodied asradio telephones containing a dual mode RF power amplifier and atwo-level output power supply coupled to the RF power amplifier. Thepower supply output provided shows voltages V1 and V2 depends on thetypes of respective modes the system operates in. The modes include thedigital mode and the analog mode which possess different demands on thesupply voltage control for the RF power amplifier when it comes tomaintaining an acceptable level of the efficiency of the RF poweramplifier.

It is a disadvantage of the known communication system, communicationdevice and method that they do not provide adequate flexibility, as toefficient adjustment concepts of the power dissipation in an RF poweramplifier included especially in a portable/mobile communicationenvironment.

It is an object of the present invention to provide a communicationdevice with reduced power consumption, not having the above drawbacks.

To this end a communication system and a communication device accordingto the invention have characterising features outlined in claims 1 and9, respectively.

It is an advantage of the communication system according to theinvention that within the notion of applying table means in order toadjust the RF output power the communication device may use severalpossible control loop concepts for communication with the base station,which concepts are applicable in order to reduce the power consumptionin an RF power amplifier during transmit sessions. Also hardwarearchitectural simplifications are principally within reach, whichreduces the power consumption even further such that the discharge timeof a battery included in portable/mobile devices may be increased or itsrequired capacity/size may be reduced.

The listed data in the table means containing the relation betweenpossible power supply control input values for the power supply andpossible RF output power values can now at wish without any waste orsurplus of RF output power be adjusted upon manufacturing to theparticulars of the circuitry used in the type of communication device.It is to be noted that the power supply output can either contain apower supply current, or a power supply voltage which will generally bethe case.

In an embodiment of a communication system according to the inventionadditional variables such as the working frequency of the RF outputsignal, and/or temperature parameters may be included as additionalvariables for fine tuning the required RF output power, in particularthe output voltage, for providing an RF output signal of the RF poweramplifier with the desired magnitude and frequency.

Preferably the table means comprise easy to implement and handle,relatively cheap memory means.

In a still further embodiment outlined in claim 4 three possibleembodiments are described in greater detail. In first and secondpossible embodiments comparator means for comparing information about adesired RF output value to the actual RF output value is included in thecommunication device, whereas in a third embodiment this comparatormeans can even be dispensed with from the communication device(s).

An embodiment of the communication system according to the inventionoutlined in claim 7 provides switching of the RF output power to maximumRF output power substantially without any loss in efficiency.

In applications wherein the RF power of the RF power output is adjustedby controlling the supply voltage to the RF power amplifier an efficientDC/DC voltage converter is preferred.

Consequently the method according to the present invention referred toabove has the advantageous characterising features outlined in claim 11.

At present the communication system, communication device and methodaccording to the invention will be elucidated further together with itsadditional advantages while reference is being made to the appendeddrawing, wherein similar components are being referred to by means ofthe same reference numerals. In the drawing:

FIG. 1 shows a first possible embodiment of a communication deviceaccording to the invention;

FIG. 2 shows a second possible embodiment of a communication deviceaccording to the invention; and

FIG. 3 shows a third possible embodiment of the communication deviceaccording to the invention applied in a communication system accordingto the invention.

FIGS. 1, 2 and 3 each show different embodiments of a communicationdevice 1, which may be used in a communication system 2 schematicallyshown in FIG. 3, together with other similar communication devices 1.The communication system 2 further comprises a base station 3 embodiedto communicate with the communication device(s) 1 and vice versa. Suchcommunication devices 1 are being used in mobile/portable communicationdevices in transceivers, pagers with acknowledgement of receipt, and thelike and in for example telephone systems or the like.

The communication device 1 comprises an RF power amplifier 4 having anRF output 5 and an RF power control input 6 for controlling themagnitude or value of the RF output power on the RF output 5. Thecontrolling of the RF output power may take place by any suitable meanssuch as for example by controlling of the duty cycle (on/off periods) orby controlling of the supply current or supply voltage of the RF poweramplifier 4, schematically depicted at 28 in the RF power amplifier 4.Description of the latter case will be adhered to in the remaining ofthe description. In a practical implementation of the communicationdevice 1 (not shown) the RF power amplifier 4 may have a power supplyinput which is separate from the RF power control input 6.

The communication device 1 also comprises a power supply 7, which may beembodied as a power supply converter for converting one power supplysignal to another. The power supply 7 having a power supply terminal 8in this case provided with a supply voltage, a control input 9 and asupply output 10 connected to the RF output power control input 6 of theRF power amplifier 4; a data receiver means 11 having an output 12connected to an receive/transmit antenna 13, an data output 14 forproviding analog or digital baseband data sent by the base station 3 andan RF input 15 connected to the RF output S of the RF power amplifier 4;and table means 16 generally embodied as memory means having a tableselection input 17 connected to the data output 14 of the data receivermeans 11 and a table output 18 connected to the control input 9 of thepower supply 7. The communication device 1 may comprise a controllableswitch 19 having two switch sides 20 and 21 connected to the powersupply terminal 8 and the supply output 10 respectively, and a controlinput 22 coupled (see dotted lines in FIGS. 1-3) to the data output 14of the receiver means 11 in the embodiments shown in the figures throughtable output 18.

The receiver means 11 comprises for example simplex- or duplex-,filter-, and demodulation means for performing a one-way or two-waycommunication link between the base station 3 and the communicationdevice 1. The RF power of the RF power signal sent through the antenna13 to the base station 3 is controlled in this case by controlling thesupply voltage applied on RF output control input 6. One of the datasent by the base station 3 to the communication device 1 contains apartfrom for example speech information about the RF output power of theoutput power amplifier sensed in the base station 3. For the embodimentsof FIGS. 1 and 2 this information concerns data about a desired signalmagnitude or value of the RF output power value. This data is fed backto the communication device 1 and is available at data output 14,generally as baseband analog or digital data. On RF output 5 the actualRF output power value is available. Both values, that is the desired andthe actual RF output power are input at respective comparator inputs 23and 24 of a comparator means 25. The comparator means 25 has acomparator output 26 which is coupled to the control input 6 throughcontrol input 9. The table means 16 contain a listing of possiblecontrol input values which are related to possible RF output powervalues. The data at data output 14 is being used for selection of theproper control input value such that a desired RF output power value isset. Several architectural concepts are possible within this context.

In the embodiment of FIG. 1 the control input value selected from thetable means 16 and available at table output 18 drives a schematicallyshown efficient DC/DC converter 27. This also holds for the embodimentsin FIGS. 2 and 3. In the embodiment of FIG. 1 the power supply 7 isschematically shown to comprises a kind of dissipative regulator means28 indicated as a variable resistor in power supply 7 in FIG. 1. Hereinthe power supply 7 is shown to have an additional control input 29connected to the comparator output 26. A coarse RF output power controlis achieved by the table output control signal on output 18, whereas afine tuning thereof takes place based on an error signal on output 26resulting from the difference between the desired and the actual valuesof the RF output power on inputs 23 and 24.

In the embodiment of FIG. 2 this error signal is being fed directly totable selection input 17 to be used as a selection signal for selectingthe appropriate control input signal for controlling the RF outputpower. However in the embodiment of FIG. 3 the communication device doesnot contain any comparator means at all because the error signal is nowbeing provided by the base station 3, sent to the communication device 1to be available on data output 14 and table selection input 17 directly.Off course the communication protocol must be designed accordingly tocope with this new concept. However it is easier to provide some kind ofhardware or software implemented comparison between an actual and adesired RF output power centrally in the base station 3 for everycommunication link with a communication device 1 than to do this in eachand every separate communication device. Furthermore this option reducesthe power consumption and hardware cost in every communication device ofthe communication system still further, because it does not contain thecomparator means 25.

In the embodiments shown the communication device 1 has the switchingmeans 19 which will be closed if the data on data output 14 indicatesthat it is desired that the RF output power is to be maximised forefficiency reasons.

In those cases wherein the RF power amplifier works in a burst mode suchas in GSM communication systems it is preferred to connect a capacitor30 to supply output 10 in order to reduce a ripple on the voltagesupplied caused by the burst. Several modifications are within reach ofthe man skilled in the art such as the inclusion of the fine tuning inthe embodiment of FIG. 1 in the embodiments of FIGS. 2 or 3. Anothermodification concerns a possible direct connection between table output18 and RF control input 6, if desired.

In view of the foregoing it will be evident to a person skilled in theart that various modifications may be made within the spirit and thescope of the present invention as hereinafter defined by the appendedclaims and that the present invention is thus not limited to theexamples provided.

What is claimed is:
 1. A communication system having at least a basestation and a communication device to communicate with the base station,the communication device comprising: an RF power amplifier having an RFoutput for coupling to an antenna and an RF output power control input,a power supply having a power supply terminal, a control input and apower supply output coupled to the RF output power control input forcontrolling an RF output power on the RF output in dependence on asignal on the control input of the power supply, and a data receivermeans for coupling to an antenna, the data receiver means having a dataoutput for providing data received from the base station, characterisedin that said data represents information about said RF output power, andthat the communication device further comprises: a table meanscontaining a listing of possible power supply control input valuesrelated to possible RF output power values, the table means having atable selection input coupled to the data output of the data receivermeans and a table output coupled to the control input of the powersupply for using said RF output power related information to select thatpower supply control input value in the table means which corresponds toa desired RF output power value, wherein the possible power supplycontrol input values contained in the table means also vary dependingupon an RF output signal frequency at the RF output for fine tuning therequired RF output power of the RF power amplifier.
 2. A communicationdevice suitable for application in a communication system according toclaim 1, the communication device comprising: an RF power amplifierhaving an RF output for coupling to an antenna and an RF output powercontrol input, a power supply having a power supply terminal, a controlinput and a supply output coupled to the RF output power control inputfor controlling an RF output power on the RF output in dependence on asignal on the control input of the power supply, and a data receivermeans for coupling to an antenna, the data receiver means having a dataoutput for providing data to be received from a base station,characterised in that said data represents information about said RFoutput power, and that the communication device further comprises: atable means containing a listing of possible power supply control inputvalues related to possible RF output power values, the table meanshaving a table selection input coupled to the data output of the datareceiver means and a table output coupled to the control input of thepower supply for using said RF output power related information toselect that control input value in the table means which corresponds toa desired RF output power value.
 3. A communication device as claimed inclaim 2, wherein the communication device is a transceiver.
 4. Acommunication system having at least a base station and a communicationdevice to communicate with the base station, the communication devicecomprising: an RF power amplifier having an RF output for coupling to anantenna and an RF output power control input, a power supply having apower supply terminal, a control input and a power supply output coupledto the RF output power control input for controlling an RF output poweron the RF output in dependence on a signal on the control input of thepower supply, and a data receiver means for coupling to an antenna, thedata receiver means having a data output for providing data receivedfrom the base station, characterised in that said data representsinformation about said RF output power, and that the communicationdevice further comprises: a table means containing a listing of possiblepower supply control input values related to possible RF output powervalues, the table means having a table selection input coupled to thedata output of the data receiver means and a table output coupled to thecontrol input of the power supply for using said RF output power relatedinformation to select that power supply control input value in the tablemeans which corresponds to a desired RF output power value, wherein thecommunication system comprises a comparator means having a first and asecond comparator input for inputting thereto said RF output powerrelated information in the form of the desired RF output power value andan actual RF output power value respectively, and having a comparatoroutput coupled to the RF power control input either directly, orindirectly through a path including the table means, said path alsopossibly including a communication link between the base station and thecommunication device.
 5. A communication system as claimed in claim 4,wherein the comparator means are included in the base station.
 6. Acommunication system as claimed in claim 4, wherein the comparator meansare included in the communication device.